Biology
Scientific paper
Dec 2010
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010agufm.p22a..08n&link_type=abstract
American Geophysical Union, Fall Meeting 2010, abstract #P22A-08
Biology
[5200] Planetary Sciences: Astrobiology, [5422] Planetary Sciences: Solid Surface Planets / Ices, [6281] Planetary Sciences: Solar System Objects / Titan
Scientific paper
Saturn’s moon Titan represents a unique locale for studying prebiotic chemistry. Reactions occurring in its thick nitrogen - methane atmosphere produce a wide variety of organic molecules. Observations by the Voyager spacecraft found evidence for six gas-phase hydrocarbons and three nitriles, along with an enveloping haze layer shrouding the surface of the moon (Hanel et al., 1981; Kunde et al., 1981; Maguire et al., 1981). More recently, the INMS instrument on the Cassini spacecraft has found evidence for organic molecules up to its mass limit of 100 Da at altitudes as high as 1200 km (Waite et al., 2005; Vuitton et al. 2007). Laboratory experiments that simulate the reactions occurring in Titan’s atmosphere produce many of the same organic molecules observed by Voyager and Cassini, along with organic precipitates known as tholins. Tholins have the general formula CxHyNz and are spectrally similar to Titan’s haze (Khare et al., 1984). Though interesting from the point of view of organic chemistry, the molecules found in Titan’s atmosphere stop short of addressing questions related to the origins of life. Oxygen - a key element for most known biological molecules - is generally lacking in Titan’s atmosphere. The most abundant oxygenated molecule, CO, is present at only ~50 ppm (de Kok et al., 2007). However, if Titan’s atmospheric organic molecules mix with water found in cryovolcanic lavas or impact melts, they may react to produce oxygen-containing, prebiotic species. In this paper, I will show that reactions between Titan tholins and low temperature aqueous solutions produce a wide variety of oxygen-containing species. These reactions display first-order kinetic behaviour with half-lives between 0.4 to 7 days at 273 K (in water) and between 0.3 and 14 days at 253 K (in 13 wt. % ammonia-water). Tholin hydrolysis is thus very fast compared to the freezing timescales of impact melts and volcanic sites on Titan, which take hundreds to thousands of years to freeze (O’Brien et al., 2005). The fast incorporation of oxygen, along with new chemistry made possible by the introduction of ammonia, may lead to the formation of biological molecules. Indeed, one tholin sample, hydrolyzed in 13 wt. % ammonia-water at 253 K and 293 K for a year, produced four identifiable amino acids. Using a combination of high-resolution mass spectroscopy and tandem mass spectroscopy fragmentation techniques, these four species have been identified as the amino acids asparagine, aspartic acid, glutamine, and glutamic acid. Advanced, prebiotic chemistry is thus possible in impact melts and cryolavas on Titan, making them important targets for future missions to that world.
No associations
LandOfFree
The Formation of Oxygen-Containing Molecules in Liquid Water Environments on the Surface of Titan (Invited) does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Formation of Oxygen-Containing Molecules in Liquid Water Environments on the Surface of Titan (Invited), we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Formation of Oxygen-Containing Molecules in Liquid Water Environments on the Surface of Titan (Invited) will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1495816